It's really difficult to diagnose a problem without actually seeing it! The cause may be a disease such as Botrytis or it could be caused by a rose midge insect.
From your description, it sounds a lot like rose midges. These tiny fly like insects, bore into rose buds and suck the juices from them causing the buds to not open properly and so the flowers are distorted. Any insecticide for roses will get rid of them but you will have to wait for the second flush before the flowers look like they should. Here are photos and more information about rose midges for you. Hope this helps.http://oregonstate.edu/Dept/nu...